COVID-19 Could Mix up Body’s ‘Fight-or-Flight’ System

A new study suggests that COVID-19 may mess with the body’s fight-or-flight response.

The coronavirus can infect many different organs in the body, including the brain. The impacts of typical COVID-19 infection on the nervous system are still unknown. The sympathetic nervous system regulates involuntary body functions such as blood pressure, pupil dilation, and body temperature; drives the body’s fight-or-flight response.

In a new study, researchers recruited a small group of young adults in the U.S. who were recovering or had recovered from COVID-19 to examine whether the coronavirus triggers changes in the sympathetic nervous system. ‘Fight-or-flight’ is an excellent mechanism in situations of high stress, but when that system is chronically elevated or stimulated, it’s not so great.

The team recruited 16 previously healthy young adults who had tested positive for SARS-CoV-2 more than two weeks before visiting the lab and had mild cases. The researchers recorded nerve activity using electrodes, blood pressure, and heart rate while the participants were resting and while the participants were sticking their hands into an ice water bath: a “cold pressor test.” They compared their results to healthy young adult controls who weren’t infected.

The researchers found that young adults recovering from SARS-CoV-2 infections had elevated sympathetic activity while resting than healthy controls. But they had no difference in heart rate, blood pressure, and sympathetic nerve activity during the cold pressor test. That means that their fight-or-flight response was more active when it didn’t have to be during rest, but the system could still respond appropriately to a threat. They also found that when the participants were asked to perform an “orthostatic challenge” or quickly stand from a sitting or lying down position, the participants recovering from SARS-CoV-2 infections had higher sympathetic nerve activity and a more significant increase in heart rate compared to healthy controls.

However, these participants were very young, healthy, and with mild symptoms. The authors say that if the results hold true in older individuals with COVID-19, there may be substantial adverse implications for cardiovascular health.

Source: The Journal of Physiology



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